This is a tale from the Dark Ages, when Ireland was beginning to grasp Christianity, and was often plagued by invading Vikings from the north. Brendan (Evan McGuire), a boy whom is fostered by his uncle, Abbot Cellach (Brendan Gleeson) of Kells, had a gift for finding trouble, even when the scope of his world is not larger than the walls that surround the abbey and the village that is protected by it. Brendan also has a gift for art, but rarely gets to indulge in the illumination of the books in the scriptorium because he had other far more mundane duties to attend to in helping the men of the abbey build the walls to protect Kells. One day as Brendan is chasing down a wild goose, he runs into the illuminators, Brother Tang (Liam Hourican), Assoua (Paul Tylack), and Square (Paul Young), and they help him catch the goose. The lucky goose is not going to be roasted, but simply is going to lose a few tail feathers. The brothers are going to use them for quills. They go to the scriptorium and tell Brendan about Aidan, the man who seems like he must be the superhero of illuminators. They also tell Brendan of the project Aidan has been working on in the island of Iona. A secret book that is like none that has even been seen before. What the brothers do not know is that the unguarded island fell prey to viking raids, and Brother Aidan (Mick Lally) is on the run. Another thing they do not know is that he carries the Book of Iona with him.